The obstacle avoidance and path planning problem
considered in this paper is applied to a SCARA type
assembly robot executing typical assembly moves in a
workspace containing unknown obstacles, Fig.1.a.
Due to the kinematic structure of the SCARA robot, this
type of motion can be considered as two dimensional if
the obstacles can be assumed to be orthogonal
parallelepipeds and the size of the end effector is
assumed small enough to be treated as a point. Under
these assumptions, the problem can be modeled as path
planning in planar robot workspace containing
polygonal obstacles, as shown in Fig.1.b. This
approach corresponds conceptually to the configuration
space approach.
The number of obstacles used in the workspace
simulation is 14. Obstacles are composed of randomly
distributed rectangles and ellipses of random sizes and
orientations. The criteria used for evaluating the
effectiveness of the controller are obstacle avoidance
(no collisions) and reaching the path endpoint to within
specified distance tolerance. The question of optimal
path generation will be considered in section 9.